Is money earned through affiliate marketing permissible or impermissible, knowing that I create backlinks for myself, which violates Google's policies, in order to rank my site higher in search results and attract visitors?

You are not permitted to use deceptive tactics by creating websites that point to your money-making site, because this violates Google's policy and is considered cheating and being "saturated with what one has not been given." This falls under the Hadith (definition): "One who is saturated with what he has not been given is like one who wears two garments of falsehood." As for what you have earned from marketing and directing customers, there is no harm in it, provided that what you directed them to is permissible. You must cease the aforementioned deceptive practices, for a believer has a monitor within himself.